High frequency switched capacitor IIR filters using parallel cyclic type circuits

In order to reduce the performance deterioration due to the finite gain bandwidth (GB) product of op-amps in switched capacitor (SC) transversal filters, parallel cyclic type circuits have been proposed. The authors consider how to implement direct form I SC IIR (infinite impulse response) filters using the parallel cyclic type circuit. The effects of finite GB products of op-amps and parasitic capacitances on the characteristics of both canonical and parallel cyclic type circuits are analyzed. A higher-frequency parallel cyclic type circuit with plural summing op-amps is also proposed. Experimental results on a biquadratic filter constructed with discrete components are also shown